1. Field of the Invention
The present invention relates generally to improvements in portable electronic devices utilizing antennas, and particularly to advantageous aspects of a collinear antenna fed by a coaxial cable that provides omni-directional composite coverage for portable radio equipment and the like.
2. Description of the Prior Art
In recent years, cordless telephones and other portable radio equipment have been put to wide practical use. Portable radio systems typically include a base unit having an antenna mounted to its housing, and a two-way handset radio unit having a second antenna that communicates with the base unit. Such portable radio equipment uses a high-frequency band ranging from 400 MHz to 2.4 gHz. The handset radio unit must operate within the area covered by the base unit to maintain receiving and transmitting functions. The antenna is arguably one of the most important parts of the base and handset units.
It is desirable for the size and weight of the base and handset units to be reduced as much as possible. As the size and weight of the base and handset units are reduced, the antenna must also be reduced in size while maintaining desired electrical characteristics, such as resonance frequency, bandwidth, and gain. Further, the market for portable radio and telephone equipment is highly competitive. As the prices of these products continue to be reduced, it is desirable to use a low-cost antenna with good repeatability and ease of assembly.